The present invention relates to a seal of the type used in surgical applications. In particular, the seal of the present invention is intended for use with therapeutic catheters which utilize a driven shaft to rotate a tool within a patient's body.
In the past, physicians performing arteriography/venography on patients were restricted to simple documentation of vascular condition. Through the use of injectable X-ray contrast material, they could generate and record X-ray images of the affected vessel, duct, or organ. Such X-ray images could be used by the physician and a surgeon to determine appropriate treatment.
Currently, physicians are actually treating patients percutaneously, using such devices as guide catheters, steerable guide wires, balloon dilatation devices, aortic balloon pumps, and vena caval filters. In most of these procedures, a guide wire is inserted into and threaded through the vessel lumen until the distal tip is at or past the site of treatment. A guide catheter (or sheath), usually preformed, is then slipped over the guide wire and advanced to a location which is just proximal to the site of treatment. Finally, the therapeutic catheter, e.g., a balloon dilatation catheter, is inserted over the guide wire and advanced to the site within the vessel lumen. Since the guide catheter and therapeutic catheter often have their distal tips located at points with high perfusion pressure (e.g., 200 mm Hg for a hypertensive patient), there is a strong tendency for blood to flow in the clearance space between the therapeutic catheter and the guide catheter. To prevent this from occurring, it is common to use a hemostasis seal, often in the form of an O-ring or rubber septum. These seals are often fitted with Luer lock fittings to permit injection of contrast solution or drugs or or to permit the extraction of fluids.
In U.S. Pat. No. 4,445,509 entitled METHOD AND APPARATUS FOR REMOVAL OF ENCLOSED ABNORMAL DEPOSITS which issued on May 1, 1984 to David C. Auth a therapeutic catheter device is described which would enable the removal of deposits from the interior wall of a patient's vessel. As more fully described in that patent, which is incorporated herein by reference, a differential cutting tool on the end of a flexible drive shaft is inserted into the affected vessel, and the drive shaft is rotated at high speed to cause the cutting tool to remove the abnormal deposits from the vessel wall.
In such catheterization systems, in which the therapeutic catheter must rotate at high speed within the guide catheter, the conventional hemostasis seal used between catheters and guide wires will not work, because the conventional resilient contact between the O-ring seal and the therapeutic catheter would lead to frictional heating and eventual destruction of the seal. Accordingly, an improved seal for use with motor driven therapeutic catheters would be desirable.